Classifier



H. HARDINGE Dec. 11, 1951 CLASSIFIER 5' Sheets-Sheet 1 Filed Jan. 15.

Dec. 11, 1951 Filed Jan. 15, 1947 H. HARDINGE 2,577,754

CLASSIFIER 3 Shee'ts/-Sheet 2 INVENTOR HARLOWE HARDINCJF:

ATTORNEYS Dec. 11., 1951 H. HARDINGE 2,577,754

' CLASSIFIER Filed Jan. '15, 1947 :s Sheets- 5heet s awe/WM HARLOWEHARDINGE mwmw Patented Dec. 11, 1951 Harlowe Hardinge, York, Pa.,

assignor to Hardinge Company, Inc., York, Pa., 8. corporation of NewYork Application January 13, 1947, Serial No. 721,679

The method and apparatus which I have invented is for separatingmaterials which have diiferent settling rates in liquid such as water;for instance, iron ore which contains materials of varying density suchas silica and iron oxide. In free settling through water, the particleswhich will settle to the bottom of any container first may be smallerparticles of the heavier material which will arrive at the bottom of anygiven container before even larger particles of a lighter material.Where the material is composed of particles all of which arehomogeneous, the size isordinarily the determining factor in the rate ofsettling. It is to be understood that this invention relates to theseparation of particles of dii-.

ferent rates of settling.

In general, my process and apparatus consists in employing a movingsurface, or platform, underneath a liquid. Onto the moving surface isdumped, or fed, unsized pulp. The fines in the pulp remains insuspension and the coarse particles rest on the moving platform. Becausethe moving platform has a motion in the liquid, for instance water, thefines are tended to be dislodged from the coarse particles by reason ofthe washing action of the water on the coarse particles after they reston the platform. Thus they have started to settle.

This type of classifier may be used with grinding mills in accordancewith common practice.

The unsized pulp is fed to my classifier at-the infiuent end areasonable distance away from the fines overflow point. The coarseparticles may be sent again to the mill to be reduced in size and may bere-fed to the classifier. It is obvious that a change in speed of themoving platform will also affect the fines discharge. At very lowspeeds, the moving platform will cause negligible disturbance near thebottom with the result that fines in addition to the coarse particlesonce deposited on the platform will tend to remain'there and be carriedup with the pre-settled coarse particles to the discharge. The fasterthe movement of the platform the greater is the agitation adjacent toit, and the greater the tendency to 4 Claims. (Cl. 209-463) fiuidmedium, with the result that when a sufficient number are present in thefluid medium they will flow as fines over the overflow end of theclassifier with the liquid.

The action and principles of this moving platform classifier areradically difierent from other types that scrape the solids by rakes,drags, or screw flights over a stationary surface. In'these types coarseand fines are mixed together, or fines are drained through, the coarse,thus holding them in the mass. The principle of depositing the unsizedpulp on the moving submerged surface permits the fines next settling onthe moving surface to be washed back into the liquid where they can bedelivered to the fines discharge point. The scraper which I employ toremove the particles deposited on the moving platform has in itself asqueezing action on the deposited particles, and liquid and fines areforced out. Thus the material on the platform gets an additionaldesliming as well as a dewatering action.

In the drawings:

Fig. l is a vertical cross sectional view, taken along the line Il ofFig. 2 looking in the direction of the arrows, of a simple form of mysystem employing a horizontal rotating disc.

Fig. 2 is a top plan view of the device shown in Fig. 1.

Fig. 3 is a vertical cross sectional view of a modification of thedevice shown in Figs. 1 and 2, taken along the line 3-3 of Fig. 4looking in the direction of the arrows.

Fig. 4 is a top plan view of the form of invention shown in Fig. 3.

Fig. 5 is a vertical cross sectional view of a form of my deviceemploying a moving belt horizontally suspended in liquid, taken alongthe line 5-5 of Fig. 6 looking in the direction of the arrows.

Fig.6 is a top plan view of the device shown in Fig. 5.

Fig. 7 is a vertical sectional view of a modification of the deviceshown in Figs; 5 and 6, taken along the line |-'I of 8 looking in thedirection of the arrows.

Fig. 8 isa top plan/view of the device shown in Fig. 7.

Fig. 9 is a top plan view of another device using a'moving belt.

Fig. 10 is a sectional view of a form of the device shown in Fig. 9taken along the line Ill-Ill of Fig. 9 looking in the direction of thearrows.

Referring to the drawings, I have shown a tank I which is circular inconfiguration and provided with a fines overflow discharge chute 2.Adapted form of chute II.

to rotate near a bottom 3 of the tank I is a disc 4 suspended on a shaft5 which is driven by suitable gearing 6 connected to a source of power,not shown. The shaft 5 is restricted in diameter as illustrated at 1where it passes through the disc 4 and a holding nut 8, or other similarholding member, holds the disc '4 on the shaft 5 so that it is rotatedwith the shaft 5.

Unsized pulp is fed through a duct 9 onto the surface of the disc 4which is rotated under the surface of water II) in the tank I. The tankI is provided with a collecting trough II at one end, in which ismounted a conveyor screw I2 driven by a source of power, not shown,which is adapted to deliver the coarse washed sands to a coarse sandsdischarge outlet I3.

Adapted to scrape the coarse particles I4 from the disc 4 is a scrapermember I5. It has been found that the scraper I5 should be set at enoughof an angle to the direction of motion of the coarse particles to scrapethem off without permitting them to be piled up to too great an extentadjacent the scraper. In other words, the angle of the scraper, it hasbeen found, should be set so as to feed the coarse particles withcomparative ease into the discharge chute I I.

Referring to the drawings, Figs. 1 and 2, it will be seen that theunsized pulp is fed through the feed pipe 9 onto the rotating disc 4,and falls through the water I onto the disc. While falling through thewater, the fines become suspended in the water. The coarse particlesafter they near the upper surface of the rotating disc 4, and when theytouch the rotating disc 4, are subjected to eddy currents which wash outmore of the fines. These fines in suspension pass over the finesoverfiow 2. The coarse particles on the disc 4 are subjected to awashing action of the water during the rotation of the disc until theyreach a point adjacent the scraper I5, at which point they are scrapedoff into the discharge The material scraped off the disc 4 falls intothe bottom of the chute, and is fed by the conveyor screw I2 to thecoarse sands discharge point I3. Here the coarse particles can be sentagain to the mill and re-fed through the unsized pulp feed pipe 9 forre-processing.

The great efilciency of my system is in part due to the eddy currentsadjacent the surface of the disc. The coarse particles as they approachthe disc 4 are subjected to a washing because of these eddy currentswhich loosens the fines and tends to keep them in suspension. Moreover,the particles after they rest on the upper surface of the disc 4 aresubjected to eddy currents and washing as the deposited particles movealong with the rotating disc. This tends to remove the fines from thecoarse particles and causes a very efllcient operation of theclassifier.

The coarse particles and the fines are not mixed together and the finesare not drained through the coarse, thus holding them in the mass, ashas been the case with other classifier systems. It is to be emphasizedthat the movement of the rotating platform causes the fines to be washedback into the liquid zone. Moreover, the action of the scraper I is tosqueeze the fines and the water out of the coarse particles, just at thepoint that the coarse particles are discharged from the classifier.

The greater the speed of rotation of the disc the greater the washingaction of the water. It is to be noted that there is greater washingaction nearthe periphery of the disc 4 than near the center, because ofthe greater speed of travel of points near the periphery than of pointsnear the center.

Now referring to Figs. 3 and 4, a somewhat similar arrangement-is shown.Here the tank I is provided with an upwardly sloping bottom I8 and thedisc 4 is arranged to rotate parallel to the bottom IS. The scraper I5is set so as to.

scrape the higher side of the disc 4. The disc 4 is arranged so that itshigher side during its rotation continually emerges above the surface ofthe liquid I0, and there is a high portion of the disc 4 which I haveindicated by the numeral I1 which lies without the water.

It is at this point that I preferably arrange to scrape, by means ofscraper I5, the coarse sands into a coarse sands discharge chute I8.Though I have shown the discharge position of the settled solids asabove the surface of the liquid they could be under the liquid, but at ahigher point than the lower point of the disc. The liquid adjacent thedisc in either case tends to rotate with the disc and the solids on thedisc, but eddy currents are produced in the liquid. Where the dischargeis above the surface of the water, some water is carried above thesurface of the liquid and washes back, carrying with it those fineswhich are lightly resting on the disc or on the coarse particles on thedisc. The liquid velocity at this point will carry them back and notpermit them to be discharged with the more tenacious portion of the loadwhich is the heavier coarser sizes. The result of this action,particularly where the discharge is above the surface of the liquid, isthat the fines will remain in suspension in the tank and they will bebuilt up to a degree where they tend to remain in suspension, andeventually will go over as fines at the overfiow 2.

Now referring to Figs. 5 and 6, I have shown a form of device in which Iuse a rectangular tank 20 in which is adapted to rotate a belt 2Imounted on suspending rollers 22, driven by some suitable source ofpower, not shown. The belt 2I is adapted to move in the direction of thearrows in a liquid 23 with which the tank 20 is filled. The belt 2| andthe belts shown in the succeeding forms of the invention are preferablysubstantially impervious. The tank 20 is provided with a fines overflow24 and a discharge chute 25, in which latter is adapted to move adischarge belt 26 mounted on rollers 21, driven by some suitable sourceof power, not shown. Adjacent one of the rollers 22 where the particlesof the pulp tend to collect, as shown at 28, I have shown a scraper toprevent the particles of the pulp from passing between the roller 22 andthebelt. A similar scraper 29, for the same purpose. is shown adjacentone of the rollers 21 over which the discharge belt rotates.

In operation the unsized pulp is fed to the classifier through the feed9 and falls on the upper surface of the moving belt 2I. I have shown thefeed pipe S'as located approximately halfway down the length of the belt2I, but it might be located further, for instance, toward the end of thetrough 20 nearer the fines overflow discharge outlet 24.

Here again the action of the moving platform formed by the belt 2| issomewhat similar to that brought about by the moving disc 4 of the formof the invention described in connection with Figs. 1 to 4 inclusive.Eddy currents are formed the fines.

belt 2| feeds the coarse particles which remain on the belt over the endof the belt as indicated ticles as shown by the arrow at the upperrights hand of the drawing, Fig. 5. There is a washin action of thecoarse particles on the belt 28 particularly where the belt 26 passesout of the water, since some of the water is entrained with particles onthe surface of the belt 28, and tends to wash the fines out of thecoarse particles.

The coarse particles which are discharged from the belt 26 can go backto the mill and can be reduced in size and again fed back to theclassifier.

The form of device shown in Figs. 7 and 8 is one in which a single beltis employed. Here the trough 20 is provided with a discharge chute 30.

There is a single belt 3| which is adapted to. .travel from a low point32 in the tank 20 to a high point 33 and the coarse particles on thebelt 3| are adapted to be discharged as indicated by the arrow into adischarge outlet 34. The belt 3| is adapted to travel on rollers 35 and36 driven by some suitable source of power, not shown, and the belt 3|may be long enough to havea sag in it, as indicated at 31.

I have shown a scraper 38 which is adapted to scrape material which hassettled on the upper surface of the lower belt section of belt 3| toprevent its passing under the roller 35, and between the roller 35 andthe belt 3|.

Here there is a definite washing action as the belt'3l passes above thesurface of the water 23 in the tank 20. The water which is carriedforward with the belt above the surface of the water in the tank 20washes back into the tank and takes with it fines. So here we again havethe washing action as the moving platform, which in this case is thebelt, passes above the surface of the liquid in the tank. This washinaction is in addition to the eddy currents which act upon the particlesby reason of the motion of the belt through the liquid.

The form of device shown in Figs. 9 and is one employing a moving belt40 which is adapted to pass over rollers 4|, 42 and 43. Power may beapplied to any of these rollers, for instance the roller 4|, so that thebelt 40 is adapted to move in the direction of the arrows. The unsizedpulp is designed to be fed through a duct 9 onto the surface of the belt40, as indicated in Fig. 10. The surface of the belt 40 lies below thesurface 44 of a body of liquid 45 in a tank 46. There is provided in thetank 46, in which the body of water 45 is contained, an overflow launder41 through which is discharged liquid containing The liquid containingthe fines flows into the overflow launder 41, as indicated by the arrowsin Fig. 10.

The belt 40, which is preferably impervious as are all the belts in theforms of the invention shown in this application for patent, is providedwith scrapers 48 which are adapted to dislodge and agitate the particleswhich tend to accumulate underneath the belt 40 at the lower end 49 ofthe tank 46. The belt is nearly horizontal at this point, though laterit rises in an upwardly sloping section andpasses out of the liquid 45.The roller 43 is provided with a scraper 50 which prevents material fromcollecting on the surface of the belt 40 which passes under the roller43. Likewise, thesurface of the roller 43 itself is overflow launder 41is a discharge launder 8| through which is adapted to be discharged theof the belt It as it passes out of the liquid 45.

In action the coarser particles tend to settle on the belt 40 as theypass along adjacent the bottom of the tank 48 on the belt 50; Here themovement of the belt 40 tends to wash out the fine particles from themass as it tends to settle on the belt 40. As the'*- coarser particlespass above the surface 44 of the liquid near the discharge launder SIfor the coarse particles. the entrained liquid washes the coarseparticles on the belt 40 and tends to loosen the fines which may haveeen deposited on these coarse particles, and causes these fines to enterinto suspension in the liquid 45. Moreover, there is a squeezing actiondue to the action of the scraper 62 which tends to wash the fineparticles free from the coarse particles as the material is scraped offthe belt 50 and passes out through the discharge launder 5|. Instead ofthe scraper 52; a jet or jets, not shown, of liquid may be employed towash the coarse particles from the belt 40. into the launder 5|.

By my apparatus and method I have avoided washing the fines through thecoarse particles and I also tend to prevent the mixing of the fines andcoarse particles to a greater extent than is possible by the usualscraping with rakes, or em? ploying drags or screw flights over astationary surface.

While I have shown certain forms of myinvensettle in a body of liquidaccording to differences in the settling rates of the particlescomprising introducing a mixture of particles of different settlingrates into a relatively quiescent body of liquid having an upper zonefree from a positive classifying current, whereby the particles fallfreely downward through the relatively quiescent zone of liquid,maintaining a path of withdrawal movement for settled particles throughthe liquid body along a moving surface which intercepts the line of fallof the particles intermediate the depth of the liquid body butsufllciently below the level of particle introduction to effect aninitial classification of the falling particles in accordance with theexisting settling rates thereof in relatively quiescent liquid,supporting and moving the particles which settle to said surface withthe same and away from the line of particle fall at a velocity inducinga positive classifying turbulence in and surrounding said path which isuniform along any line taken. across the path and parallel thereto, toeffect an additional classification of particles adjacent said pathwhich is uniform along any line taken across said path and parallelthereto, and controlling the speed ofthe said face which intercepts theline of fall of the particles intermediate the depth of the liquid bodybut sufficiently below the level of particle introduction to effect aninitial classification cf the falling particles in accordance with theexisting settling rates thereof in relatively quiescent liquid,supporting and moving the particles which settle to said surface withthe same and away from the line of particle fall at a velocity inducinga positive classifying turbulence in and surrounding said path which isuniform along any line taken across the path and parallel thereto, toeffect an additional classification of particles adjacent said pathwhich is uniform along any line taken across said path and parallelthereto, controlling the speed of the said moving surface to obtain thedesired classification, removing particles which remain settled in saidpath from the liquid body at one point, and removing particles insuspension in the liquid body together with liquid at another point.

3. A method of classifying particles which settle in a body of liquidaccording to differences in the settling rates of the particlescomprising introducing a mixture of particles of different settlinerates into'a relatively quiescent body of liquid having an upper zonefree from a positive classifying current, whereby the particles fallfreely downward through the relatively quiescent zone of liquid,maintaining a path of withdrawal movement for settled particles throughthe liquid body along a substantially plane and moving surface whichintercepts the line of fall of the' particles intermediate the depth ofthe liquid body but sufliciently below the level of particleintroduction to effect an initial classification of the fallingparticles in accordance with the existing settling rates thereof inrelatively quiescent liquid, supporting and moving the particles whichsettle to said surface with the same and away from the line of particlefall at a velocity induc- Y in a positive classifying turbulence in andsurrounding said path which is uniform along any line taken across thepath and parallel thereto, to effect an additional classification ofparticles adjacent said path which is uniform along any line takenacross said path and parallel thereto, 6

controlling the speed of the said moving surface to obtain the desiredclassification, removing particles which remain settled in said pathfrom the liquid body at one point, removing particles in suspension inthe liquid body together with liquid at another point, and subjectingthe particles remaining settled in'said path to a desliming squeezingaction adjacent the point of removal thereof from the liquid body.

4. A method of classifying particles which settle in a body of liquidaccording to diflerences in the settling rates of the particlescomprising introducing a mixture of particles of different settlingrates into a relatively quiescent body of liquid having an upper zonefree from a positive classifying current, whereby the particles fallfreely downward through the relatively quiescent zone of liquid,maintaining a path of withdrawal movement for settled particles throughthe liquid body along a substantially plane and moving surface whichintercepts the line of fall of the particles intermediate the depth ofthe liquid body but sufficiently below the level of particleintroduction to effect an initial classification of the fallingparticles in accordance with the existing settling rates thereof inrelatively quiescent liquid, supporting and moving the particles whichsettle to said surface with the same and away from the line of particlefall at a velocity inducing a positive classifying turbulence in andsurrounding said path which is uniform along any line taken across thepath and parallel thereto, to effect an additional classification ofparticles adjacent said path which is uniform along any line takenacross said path and parallel thereto, controlling the speed of the saidmoving surface to obtain the desired classification, and moving theparticles which remain settled. in said path and the particles insuspension in the liquid body along parallel paths to differentdischarge points.

HARLOWE HARDINGE.

REFERENCES CITED i'he following references are of redord in the die ofthis patent;

UNITED STATES PATENTS

